This invention relates to polymeric sheets and articles formed therefrom. More particularly, this invention relates to polymeric sheets and articles formed therefrom, especially elastomeric sheets and articles, wherein the sheets and articles have improved resistance to cutting by a sharp edge.
Polymeric sheets, particularly elastomeric sheets, having improved resistance to cutting with a sharp edge have long been sought. Cut-resistant sheets are useful for providing cut resistance to products ranging from medical equipment to surgical gloves.
Cut-resistant textile articles are disclosed, for example, in U.S. Pat. Nos. 5,200,263; 5,119,512; 5,146,628; and 5,224,363.
U.S. Pat. No. 5,200,263 teaches a puncture- and cut-resistant composite material and articles, e.g., gloves, made therefrom, wherein the composite material is composed of at least one elastomer layer containing a plurality of platelets oriented substantially parallel to the plane of the elastomeric layer, each of the platelets being a small, thin element substantially impervious to normally encountered puncturing and/or cutting by sharp instruments. This patent teaches the use of particles having a relatively large diameter, e.g. from about 1.5 mm to about 4.0 mm.
U.S. Pat. No. 5,119,512 discloses cut-resistant yarn and fabrics and gloves made therefrom. The reference further teaches a cut-resistant article composed of a cut-resistant jacket surrounding a less cut-resistant member. The cut-resistant jacket contains a fabric made from a yarn containing at least one high strength, longitudinal strand wrapped with a fiber. The less cut-resistant member is a rope, webbing, strap, hose or inflatable structure. The reference further teaches a highly cut-resistant composite yarn composed of at least two fibrous materials, wherein at least one fibrous material is cut-resistant and at least one fibrous material has a high level of hardness.
U.S. Pat. No. 5,224,363 discloses cut resistant protective garments, e.g., gloves, which are formed from high strength composite strands. The composite strands contain a cut-resistant core material coated with a fluid impervious material. The cut-resistant core material may be Kevlar(copyright), aramid strands, stainless steel strands, or a combination of Kevlar(copyright) and stainless steel strands. The fluid impervious coating may be polyurethane or vinyl.
U.S. Pat. No. 5,146,628 discloses protective gloves coated with a polyurethane material. The polyurethane coating is abrasion-resistant, cut-resistant, flexible and soft and provides the glove with slip-resistance and gripping properties.
Puncture-resistant textile articles are also known in the art. Reference is made, e.g., to U.S. Pat. Nos. 5,363,930 and 5,087,499.
U.S. Pat. No. 5,363,930 teaches a thin elastomeric sheet material and protective clothing, e.g., gloves, made therefrom. The elastomeric sheet material has enhanced puncture-resistance and is prepared by embedding thin plate-like non-elastomeric particles in an elastomeric matrix. The preferred non-elastomeric particles have a hardness on the Mohs scale of at least 5 and include metals, ceramics and crystalline minerals. The particles used in this patent have a relatively large diameter, for example, about 3 mm.
U.S. Pat. No. 5,087,499 discloses puncture-resistant and medicinal treatment garments, e.g., gloves, formed from fibers such as Kevlar(copyright) or Spectra(copyright). The fibers may be coated with an abrasive material such as, e.g., a mixture of ceramic or metallic particles and a polymeric resin.
U.S. Pat. No. 5,051,301 discloses composites and textile articles made therefrom, wherein the composites have improved toughness and contain a ceramic matrix and a plurality of layers of boron nitride-coated fibrous material. The ceramic matrix may be used in combination with an organic binding material.
Copending, commonly assigned U.S. patent application Ser. No. 08/752,297, filed Nov. 19, 1996, discloses the manufacture of cut-resistant garments such as gloves made from cut resistant fibers.
Although cut-resistant polymeric sheets are known in the art, it is continually desirable to provide polymeric sheets having improved cut-resistance.
Furthermore, it is desirable to impart improved cut-resistance to polymeric sheets by means of particles having relatively small diameters. Particles with relatively small diameters are easier to process than particles with relatively large diameters. Thus, small-diameter particles tend to produce smoother sheet surfaces than do large-diameter particles. However, particles which are too small, e.g., less than about 0.25 microns, tend to be less effective for providing cut-resistance. Larger-size particles provide better cut-resistance but also rougher sheet surfaces. Thus, it is desirable to use particles which provide both effective cut-resistance and relatively smooth sheet surfaces.
In addition, it would be desirable to provide cut-resistant polymeric sheets which form articles having improved flexibility and comfort as well as increased cut-resistance.
Accordingly, a primary object of this invention is to provide polymeric sheets, particularly elastomeric sheets, having improved cut-resistance.
A further object of this invention is to provide polymeric sheets having improved cut-resistance, wherein such sheets contain hard particles having relatively small diameters.
Another object of this invention is to provide cut-resistant polymeric sheets which form polymeric articles having improved cut-resistance, improved flexibility, and improved comfort.
These and other objects which are achieved according to the present invention can be discerned from the following description.
The present invention provides a polymeric sheet having excellent cut-resistance, containing:
(A) a polymeric material, and
(B) a hard filler distributed in the polymeric material, the hard filler having a Mohs Hardness value of at least about 3.0, the hard filler being in the form of particles having an average diameter which is sufficient to provide cut-resistant properties to said polymeric material but which is no larger than about 5 microns.
The present invention is further directed to cut-resistant articles formed from the cut-resistant polymeric sheet of this invention.
The present invention is also directed to composites containing the cut-resistant polymeric sheet of this invention laminated onto a cut-resistant or non-cut-resistant textile fabric. The present invention further includes articles composed of the aforementioned composite.
In preferred embodiments of the invention, the polymeric material is an elastomer, and the polymeric sheet is an elastomeric sheet.
An important advantage of the present invention is that improved cut-resistant properties are imparted to polymeric sheets by hard filler particles having relatively small diameters. Thus, articles formed from such polymeric sheets not only have excellent cut-resistance but also improved flexibility and comfort and relatively smooth surfaces.